Equity & options

ISO vs NSO

Also called incentive stock options, non-qualified stock options, ISOs and NSOs

ISOs are tax-advantaged stock options available only to employees, potentially taxed at capital gains rates if holding requirements are met; NSOs can be granted to anyone and are taxed as ordinary income on the spread at exercise.

The practical differences

Incentive stock options can only go to employees. Non-qualified stock options can go to employees, advisers, contractors and board members, which is why adviser grants are almost always NSOs.

On exercise, an NSO holder owes ordinary income tax on the spread between strike and fair market value, withheld at the time. An ISO holder owes nothing in regular income tax at exercise, though the spread counts toward alternative minimum tax.

If an ISO holder holds the shares more than two years from grant and one year from exercise, the entire gain is taxed at long-term capital gains rates. Miss either window and the ISO is treated as an NSO.

Limits and expiry

ISOs carry a $100,000 limit on the value of options first becoming exercisable in any calendar year, measured at grant-date value. Anything above that is treated as an NSO.

ISO status also ends 90 days after employment ends. Leavers who cannot fund an exercise within that window see their ISOs convert to NSOs, which is a common and unpleasant surprise. Some companies now offer extended exercise windows, accepting the conversion in exchange for fairer treatment of leavers.

Worked example

  1. An employee holds 10,000 options with a $1.00 strike. Fair market value at exercise is $6.00.
  2. Spread: 10,000 x $5.00 = $50,000.
  3. NSO: $50,000 taxed as ordinary income at exercise, withheld immediately.
  4. ISO: no regular income tax at exercise, but $50,000 counts toward AMT. If held two years from grant and one from exercise, the eventual gain is long-term capital gains.

Common questions

Can advisers receive ISOs?

No. ISOs are restricted to employees. Advisers, contractors and non-employee directors receive NSOs.

What is the $100,000 ISO limit?

Only $100,000 of options, measured at grant-date value, may first become exercisable in a calendar year with ISO treatment. The excess is treated as NSOs.

What happens to ISOs when you leave?

ISO status expires 90 days after employment ends. Options exercised after that are treated as NSOs, which is why extended exercise windows have become a live topic.

Related terms

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